The head of a wood-type golf club such as a driver or a fairway wood is often hollow and made of metal. A hollow wood-type golf club head has a face part for striking the ball, a crown part comprising the upper surface part of the golf club head, a sole part comprising the bottom surface part of the golf club head, a side part comprising the side surface part on the toe side, the back side and the heel side, and a hosel part. A shaft is inserted into the hosel part and secured using an adhesive. Recently, a golf club known as a utility club has become widely available. One type of utility golf club that has become widely available is a golf club with a hollow head resembling that of a wood-type golf club head (that is, having a face part, a sole part, a side part, a crown part, and a hosel part).
Aluminum alloys, stainless steel, and titanium alloys are used as the metal constituting the hollow golf club head, but titanium alloys have become more widely used in recent years.
The hollow golf club head described in Patent Document 1 includes ribs provided on the inner surface of the sole part in a direction linking the face part and the back-side of the side part. The hollow golf club head described in Patent Document 2 includes receiving parts provided inwardly near the toe and near the heel so as to interpose the rearmost portion of the side part on the back side, projection parts projecting inwardly on the back side of the side part, ribs provided in the toe-to-heel direction between the receiving parts and the projection parts, and ribs provided in the top-to-sole direction from each receiving part and projection part. The hollow golf club head described in Patent Document 3 includes ribs provided so as to extend from the inner surface of the sole part towards the inner surface of the crown part.
The hollow golf club head described in Patent Document 4 includes a restraint member extending from the inner surface of the crown part towards the sole part. The hollow golf club head described in Patent Document 5 includes ribs provided linearly on both the outer surface and the inner surface of the golf club head.